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This invention relates to an apparatus for processing microelectronic workpieces, such as semiconductor workpieces, glass photomask plates, memory media workpieces, workpieces used in the formation of micro-mechanical devices and/or components, etc. More particularly, the invention is directed to a seal arrangement for use in a microelectronic workpiece processing system that assists in improving the workpiece processing yield.
In the production of integrated circuits and other microelectronic components, etc., the microelectronic workpieces undergo multiple processing steps. The basic material for the workpiece substrates may be silicon, glass, ceramic materials of various sorts or other similar materials of very thin waferlike configuration. This basic substrate is subjected to coating, etching, and cleaning processes and it is extremely important that each processing step is performed with the greatest possible yield thereby lowering production costs.
Microelectronic workpieces have been processed by spinning them about a vertical axis where the wafers or masks are stacked vertically as described in U.S. Pat. No. 3,760,822 with various holding mechanisms such as vacuum chucks. This has led to further disadvantages where the workpiece may be only processed on one side at a time without a significantly different processing rate, wherein the topside processes at a much faster rate than that of the underside.
Other processing devices such as described in U.S. Pat. No. 3,970,471, process each wafer individually. Although the wafer is rotated about a horizontal axis, such a device can only process a single wafer at each station which may be expensive and time consuming.
To eliminate many of the problems noted above, the assignee of the present invention developed a wafer processing system and set forth and claimed the system in U.S. Pat. No. 4,300,581, titled xe2x80x9cCentrifugal Wafer Processorxe2x80x9d, issued Nov. 17, 1981. The invention set forth therein permits the processing of a plurality of wafers at the same time in a carrier. In accordance with that invention, microelectronic workpieces are processed by inserting them into the carrier and placing the carrier in a rotor, which rotates around a substantially horizontal axis (although disposed at a slight angle). Various processing fluids may be applied to the workpieces uniformly through the spray nozzles while the workpieces are being rotated.
The foregoing system includes built-in shock absorbers that extend vertically from a frame that supports a bowl into which the carrier is inserted. The shock absorbers assist in reducing the transfer of vibrational energy to the carrier. The reduction of vibration energy transfer facilitates a greater processing yield since the workpieces are not subject to damaging mechanical stresses and strains. The present inventors have recognized a further manner in which to reduce the vibration energy transfer using a direct drive motor assembly having one or more shock absorbing structures associated therewith. A still further problem present in the prior apparatus is the sealing of the motor to isolate it from exposure to materials, such as processing fluids. The present inventors have provided a unique solution to this problem by providing a seal about the rotor of the motor.
An apparatus for processing a microelectronic workpiece, such as a semiconductor wafer, is set forth. The apparatus comprises a processing bowl that defines a processing chamber. A seal is provided to assist in removing fluids, such as processing fluids, from the processing chamber that are in the proximity of the seal. Further, the seal is provided to assist in preventing the fluids from entering the motor. To this end, flow generating threads and expulsion threads are provided at an end of a shaft assembly that is connected to be driven by the motor. A member substantially surrounds at least a portion of the flow generating threads and at least a portion of the expulsion threads. Together, the member defines a chamber with the shaft assembly. Rotation of the shaft assembly results in corresponding rotation of the flow generating threads and expulsion threads to drive fluids proximate the shaft assembly to an exhaust while concurrently assisting in preventing such fluids from entering the motor.